The present invention generally relates to an image output apparatus, and more particularly to an image output apparatus for displaying and printing image data using an erasable recording medium sheet on which image data can be recorded and erased so that the sheet can be reused for displaying and printing image data.
FIG. 1 shows an image output device for outputting image data on a recording medium. In the device shown in FIG. 1, a sheet supplying unit 1, a recording unit 3 having a writing member 2, and a display unit 4 are provided. A plurality of recording medium sheets 5 are accommodated in the sheet supplying unit 1. The sheet supplying unit 1 includes a roller 8 for transporting one of the sheets 5. One of the sheets 5 is fed from the sheet supplying unit 1 to the recording unit 3. The recording unit 3 includes a platen roller 6 and a sheet guiding passage 7.
In order to display the sheet 5 at a display position on the displaying unit 4, the roller 8 is driven in accordance with a signal from a control part (not shown), so that the sheet 5 is transported from the sheet supplying unit 1 to the recording unit 3. The sheet 5 is transported to the platen roller 6 through the sheet feeding passage 7 by rotation of the roller 8, and it is further transported to the writing member 2 by rotation of the platen roller 6, so that information is written to the sheet 5 by the writing member 2. After the writing is finished, the sheet 5 is transported to the displaying unit 4, so that the sheet 5 is set at a display position on the displaying unit 4. When the sheet 5 on the displaying unit 4 is not needed after it is displayed, the sheet 5 is manually removed by an operator.
Conventionally, there is another image output device in which a display part using a belt-like erasable heat-sensitive recording medium, a printing part using a non-erasable heat-sensitive recording medium, and a thermal head shared by the display part and the printing part are provided. In this image output device, it is impossible to automatically return a recording medium sheet 5 from the displaying unit 4 to the sheet supplying unit 1.
There is a different image output apparatus which utilizes a belt-like erasable heat-sensitive recording medium sheet, and a heating unit, so that the sheet is set to a suitable temperature by the heating unit. When data is written to the sheet, the sheet is heated to a writing temperature. In order to erase the data written to the sheet, the sheet is cooled to an erasing temperature. When the sheet with the recorded data is displayed, the sheet temperature is maintained at a suitable temperature. Generally, erasable recording media used for image output apparatuses are classified into photochromic recording media, electrochromic recording media, and thermochromic recording media.
Japanese Laid-Open Patent Publication No.63-184782 discloses an image displaying device which utilizes a recording medium sheet formed into two thermochromic layers. Japanese Laid-Open Patent Publication No.55-154198 discloses a thermochromic recording medium which a hybrid film made of a high-molecular organic compound and a low-molecular organic compound. The thermochromic recording medium becomes white or transparent depending on the film temperature when the film is heated to a temperature higher than or lower than the upper temperature limit.
Japanese Laid-Open Patent Publication No.61-258853 discloses a blended composition for an erasable heat-sensitive recording medium which can control light tranmission by heat and can memorize color. The composition comprises a blended material of two component system showing a phase diagram of lower critical solution temperature (LCST) type such as a blended material of two components: vinylidene fluoride polymer and (meth)acrylic ester polymer. One of the two components is a low molecular polymer. It is suggested in Japanese Laid-Open Patent Publication No.61-258853 that if the composition disclosed therein is used for the recording medium, the recording medium shows the erasable recording characteristic since the opaque conditions of the recording medium can be maintained at normal temperature.
There is a known image output method in which the light scattering due to the change of the orientation of liquid crystal high molecular particles is utilized so that an image can be visualized at normal temperature due to changes in the opacity of the recording medium. Japanese Laid-Open Patent Publication No.57-94780 discloses an image output device utilizing the image output method as mentioned above. Japanese Laid-Open Patent Publication No.63-38927 discloses an over-head projector (OHP) device utilizing the image output method as mentioned above.
In a conventional image output apparatus as mentioned above, the recording medium sheet to which information is written is merely placed on the displaying unit. If the display of the sheet is no longer necessary, an operator must manually remove the sheet from the displaying unit. There is no mechanism to automatically return the displayed sheet from the displaying unit to the sheet supplying unit or other portions in the above mentioned image output apparatus. In addition, it is impossible to eject the displayed sheet from the apparatus, and it is difficult to re-use the recording medium sheet after data is written to the sheet and the sheet is displayed. However, there is a demand for the re-use of the recording medium sheet, used by the image output apparatus, in order to achieve filing, copying and displaying of the sheet on a different image processing apparatus.